X-ray detection is widely applied in technical fields such as medical treatment, security, non-destructive detection and scientific research, and plays an important role in national interest and people's livelihood. At present, x-ray digital radiography (DR) detection technology appeared in the late 90's has become a commonly used X-ray radiography detection technology. An x-ray DR system usually utilizes a flat-panel detector in which a size of pixel unit can be smaller than 0.1 mm, and consequently obtains an image quality and resolution almost commensurate with that using photography films; furthermore, defects involved in photos from photography films can be eliminated, and image processing by using computers can be facilitated. According to a difference in electronic conversion modes, the x-ray technology can be classified into direct DR type and indirect DR type.
A flat-panel x-ray radiography detector of direct DR type includes a radiographic receiver, a command processor and a power supply. The radiographic receiver includes a scintillation crystal screen (Gd202 S or CsI), a large-scale amorphous silicon sensor array and a read circuit. As illustrated in FIG. 1, the scintillation crystal screen converts X-ray photons into visible light, then the large-scale amorphous silicon sensor array closely attached to the scintillation crystal screen converts the visible light into electrons, and then the read circuit digitizes the electrons and delivers digital signals to a computer so as to generate digital images for display.
An existing x-ray radiography detector of direct DR type is illustrated in FIG. 1, including: an electrode plate 2 connected to a power supply 1; an insulating plate 3, an amorphous silicon semiconductor layer 4, an electron blocking layer 5 and a charge collection layer 6 which are sequentially formed at a side of the electrode plate 2; and an acquisition circuit 8 disposed in an underlying layer. As illustrated in FIGS. 2 and 3, the amorphous silicon semiconductor layer 4 converts the photons of X-ray 9 passed through the electrode plate 2 and the insulating plate 3 into visible light, and converts the visible light into electrons, which are read and delivered to the acquisition circuit 8 by the electrode plate 810 (the charge collection layer in FIG. 1) and then output upon amplification. The acquisition circuit 8 includes a storage capacitor Cst 85 (a first electrode 807 and a second electrode 809), a transistor and an electrode plate 810 connected to the first electrode 807 of the storage capacitor; wherein the second electrode 809 of the storage capacitor is connected to a ground line 820; a source electrode 814 of the transistor is connected to the first electrode 807 and the electrode plate 810, and a drain electrode 824 of the transistor is connected to an amplifier.
During a manufacture process of such X-ray radiography detector of direct DR type, it needs to form a gate electrode 801, an insulating layer 802, an active layer 814, a source electrode 814, a ground line 820, a drain electrode 824, a first passivation layer 806, a first electrode 807 of storage capacitor, a second passivation layer 808, a second electrode 809 of the storage capacitor, a planarization layer 800 and an electrode plate 810 on a substrate 7; which requires ten to twelve times of masking processes. As a result, the manufacture of the existing X-ray radiography detector is complicated with frequent usage of masks and relatively higher cost.